Semiconductor devices are prepared by dicing a large-diameter silicon wafer with IC circuits formed thereon into chips, thermocompression bonding a chip to a lead frame via a liquid adhesive called die bonding agent, wire bonding between electrodes of the chip and the lead frame, and encapsulating thus obtained device to protect the chip. For encapsulating the device, resin transfer molding is most commonly used because of its mass productivity and low production costs.
To downsize and diversify electric and electrical appliances, packaging technology in which no lead frame is becoming common, for example, area array packaging such as Chip Scale Package (CSP), Stacked Chip Scale Package, System in Package (SiP). Devices in these packagings are required to have higher resistance to thermal shock than before.
In addition, higher reflow temperature of 265° C. is required for lead-free solder. Among materials used for the packagings, a die bonding agent is considered to allow wider modification than others. For this reason, a die bonding agent is required which meets the requirement of the resistance to thermal shock.
Japanese Patent Application Laid-Open No. H06-333963 describes adding to a die bonding agent a flexibilizer such as a reaction product of a modified silicone oil having hydroxylphenyl groups and an epoxy resin. It is described that the use of the flexibilizer in combination with an imidazole derivative provides a cured product which has no void and is resistant to thermal shock.